From this we see the last 5 digits repeat in a cycle of 5 * 100 = 500.

But we also notice that the sixth digit from the end is incremented by 1 for every repetition through the cycle of 500 terminal 5 digits, so 10 cycles of the last 5 digits will produce a repetition of the last 6 digits, so that is a cycle of 500 * 5 = 5000.